1. Field of the Invention
The present invention pertains to apparatus for use with internal combustion engines to reduce noxious gases emitted therefrom. In particular, the present invention pertains to apparatus particularly suitable for use with natural gas fueled engines and for converting nitrogen oxides, carbon monoxides and unburned hydrocarbons from the exhaust of such engines to less noxious compounds and for reducing the noise emitted therefrom.
2. Brief Description of the Prior Art
Silencers or mufflers for internal combustion engines have existed for many years. Most industrial silencers utilize some type of housing in which is mounted various types of baffles or other silencing components for reducing the noise produced at the exhaust of an internal combustion engine.
In addition to noise reduction, a great deal of attention has also been directed, in recent years, to reducing the noxious gases emitted from the exhaust of an internal combustion engine, e.g. nitrogen oxide, carbon monoxide and other unburned hydrocarbons. As interest and concern about pollution of the atmosphere increases, the search continues for effective means for reducing these noxious emissions. Increased regulation by state and federal authorities mandates that more effective means be found. The most effective means of reducing noxious emissions at this time appears to be those methods which utilize some type of catalyst which converts the noxious gases to water, nitrogen, carbon dioxide and other harmless emissions.
Most exhaust emission control apparatus of the prior art utilizes separate devices for noise reduction and noxious gas reduction. This is probably due to the fact that silencers or mufflers are commonly made by one manufacturer and catalytic converters by another. Since these devices are made separately but must be connected in series to an engine exhaust, the pressure drop therethrough is relatively great, resulting in decreased fuel efficiency. In addition to increased operating expense, two separate units usually result in greater installation and maintenance costs. In recent years, some emission control apparatus have been manufactured which combine the functions of noise reduction and noxious gas reduction in a single device or apparatus. Examples may be seen in U.S. Pat. Nos. 4,209,493 and 4,601,168. While these devices are substantially more efficient and cost effective than those of the prior art, continued concern over noise and air pollution dictates even more efficient and effective apparatus.